Articulating body joints are surfaced with hyaline cartilage, which is a very durable low coefficient of friction natural material. These surfaces are often damaged when subjected to high repeated loading, such as when one runs. This is particularly true for lower body compressive joints such as the ankle, knee, hip and spine.
Resurfacing of the cartilage surfaces is a large area of study in the orthopaedic industry. One technique used for resurfacing of the cartilage is referred to as microfracture. Rather than replacing the damaged articular cartilage with an artificial implant, microfracture stimulates the body to replace the surface with a fibrous cartilage. Fibrocartilage is not as robust and does not have the low coefficient of friction that hyaline cartilage does, but it does provide patients with reduced pain and enables them to participate in an active lifestyle.
Microfracture procedures are generally performed by first removing the damaged layer of cartilage. The damaged layer can vary from about 1 to about 6 mm in thickness. A sharp microfracture pick is then driven about 2 to about 5 mm through the underlying subchondral bone to a blood supply. When the pick is removed, a small channel remains. A series of channels can be formed in the subchondral bone such that blood travels along the channel and clots in the area of the removed cartilage.